Movements of the eyes shift the retinal image by an amount equal to and opposite from that of the eye movement. The visual system must separate real world motion from retinal image shifts caused by eye movements so that motion of objects in the real world can be analyzed. The question is how and how well the neurons in the visual motion pathway can represent real world motion during movements of the eyes. Neurons in extrastriate area MT and the medial superior temporal area (MST) are selective for image direction and speed. In addition, some cells in area MST carry signals related to movements of the eyes. The experiments have two main goals: 1) to assess basic visual and smooth pursuit eye movement-related properties of MT and MST cells in awake, behaving monkeys; 2) to assess the degree to which visual and oculomotor signals interact in these same neurons. We will investigate these putative interactions by comparing responses to particular patterns of retina motion as monkeys both fixate and make smooth pursuit eye movements. Comparing speed and direction tuning under these viewing conditions will reveal the degree to which the responses of MT and MST cells compensate for movements of the eyes and represent motion of objects in the world.